Planes make trips across the U.S. all the time. Nothing too special, right? Except a solar-powered one just traveled cross-country for the first time.

The Solar Impulse, which is a solar-powered plane, traveled from San Francisco in early May to John F. Kennedy International Airport in New York. It finally landed at 11:09 p.m. last Saturday night.

What took the plane so long, you ask? It made stops in between San Francisco and New York in cities such as Phoenix, Dallas-Fort Worth, Dulles, St. Louis and Cincinnati.

The Solar Impulse is equipped with about 11,000 solar cells on a pair of jumbo wings. It would fly from early morning to late at night, collecting sunlight for a completely fuel-free flight. The aircraft would reach 30,000 feet off the ground at a top speed of 45 mph.

The Solar Impulse is about the size of a small car, running only on the power equivalent to a "small motorized scooter" according to The Washington Post.

While the plane successfully made it to New York, the flight wasn't perfect. An eight-foot tear on the lower left side of the wing occurred during the last leg of the trip, which was discovered in New Jersey. The Solar Impulse was supposed to pass the Statue of Liberty before landing, but issues with the tear caused the plane to have to land three hours early at JFK instead.

“It was a huge success for renewable energy,” said Andre Borschberg, pilot of the Solar Impulse. “The only thing that failed was a piece of fabric.”

This flight was a test before developing a more advanced version, which will make a trip around the world in 2015.

It has already flown through the night from energy stored in the batteries, and was in the air for a 26 hour continuous flight. I don't know if there was enough surplus solar energy during the day to charge during the night or whether the plane left the ground with a full battery, but the two scenarios aren't that far apart.

Once they do enough flights to be confident in reliability, they'll match the Rutan Voyager and even surpass it. Circumnavigating the earth is already in their near term plans.

I think it'd be a pretty remarkable feat to go airborne for indefinite periods of time without needing to go into orbit.

PV solar efficiency will have to get substantially better before they can circumnavigate the globe. Planes are typically built with a safety factor of 1.5 (you calculate how strong the parts have to be to withstand maximum estimated loading, then build them 1.5x stronger). Experimental aircraft that carry people sometimes push this down to 1.25. Unmanned aircraft and missiles can push this down to about 1.1.

That they experienced a tear in the wing during the flight indicates they were really close to a 1.0 safety margin. It's plausible to fly a person in something with that small a safety margin if it's done over land. But no way do you want to be doing it over water. So PV efficiency will have to get better so they can build a more robust plane before safe transoceanic flights are feasible.

quote: I think it'd be a pretty remarkable feat to go airborne for indefinite periods of time without needing to go into orbit.

That was already accomplished back in the 1990s with solar powered UAVs. This solar plane is notable in that it carries (or can carry) a pilot.